Fix #89 by fixing Error's type.

Richard Eisenberg · Richard Eisenberg · commit 077aee54a07f · 2015-09-16T16:27:41.000-04:00
diff --git a/src/Data/Singletons/TypeLits/Internal.hs b/src/Data/Singletons/TypeLits/Internal.hs
@@ -140,8 +140,9 @@ withKnownNat SNat f = f
 withKnownSymbol :: Sing n -> (KnownSymbol n => r) -> r
 withKnownSymbol SSym f = f
 
--- | The promotion of 'error'
-type family Error (str :: Symbol) :: k
+-- | The promotion of 'error'. This version is more poly-kinded for
+-- easier use.
+type family Error (str :: k0) :: k
 $(genDefunSymbols [''Error])
 
 -- | The singleton for 'error'
